Woodrow Wilson -- future president of Princeton, author of numerous best-selling books, and possibly the greatest pedant ever to reach the heights of power in the U.S. -- did not read at all until he was 9, and could not read well until he was 11.
On the other hand Terry Tao, mathematics prodigy who went on to win the Fields Medal, taught himself to read at 2.
How to design a school system to accommodate the diverse abilities of millions of children is a problem of enormous magnitude, quite possibly beyond our ability to solve. But it seems to me that we need more flexibility, not more bureaucracy, no matter how well intentioned. The premise of No Child Left Behind and similar laws, that all children can learn the same things at the same ages, is simply wrong.